Understanding reverse DNS better

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1

We have a /24 from one of our upstream providers that we handoff to a customer. The /24 has been SWIPd to us, and we have nameservers setup with ARIN against that record.

Twice now this information has just "disappeared". That is, if do reverse DNS lookups, they returns nothing, whereas they were just working fine earlier. If you do an NS lookup on the block, it returns nothing. The /24 blocks immediately surrounding us continue to work just fine. If we do a lookup directly against our nameserver, it works just fine.

It's like the nameserver information against that reverse DNS is just magically gone.

The ARIN record looks good, nothing has changed. Last time, our upstream resubmitted the info so it would repopulate, and it started working again soon there after. I admit to not being the smartest one with how these records work: is the problem with the upstream, or ARIN's database, or is there not enough information to tell?

Thanks,
Caleb

2

I suggest doing something like:

dig +trace -x 204.42.254.5

You can watch the delegation authority for the in-addr at each stage.

- Jared

3

+1, also a quick check to make sure your name servers are actually set can be done with host.. host -t ns 0.168.192.in-addr.arpa

4

Excellent, the +trace option is most helpful, thank you.

5

I use Squish (www.squish.net/dnscheck) for this purpose. Reasonable
web interface and gives lots of info about where things are breaking
down...

6

squish.net/dnscheck is great, except when I've had problems with it, or
wanted a second opinion. Does anyone know another site that offers much
the same functionality?

Jethro.

. . . . . . . . . . . . . . . . . . . . . . . . .
Jethro R Binks, Network Manager,
Information Services Directorate, University Of Strathclyde, Glasgow, UK

The University of Strathclyde is a charitable body, registered in
Scotland, number SC015263.

7

google(dns doctor)
google(zonecheck)

(various places host that tool and you can install it locally too)

Oh and this tool called 'dig' which is really amazing.

Greets,
Jeroen

8

I use Squish (www.squish.net/dnscheck) for this purpose. Reasonable
web interface and gives lots of info about where things are breaking
down...

Seems to be having issues:

Finding servers for . from A.ROOT-SERVERS.NET (198.41.0.4)

         Error: Resolve for NSs of . to A.ROOT-SERVERS.NET (198.41.0.4) failed: query timed out

-Hank

9

If you like a nice graphic schematic try:
http://www.zonecut.net/dns/index.cgi

-Hank